I do have barn doors. It seems there are three ways to do it. Build one that is connected to the door hinges on the right, build one into the bumper itself or build one that attaches to the receiver. I think the latter will be the least expensive but, I do need to replace my bumper anyway since someone nailed my burb in a parking lot and drove off.

Personally, I'd build or get one that swings from the drivers side and doesn't go all the way across. The reasoning for this is the passenger side door opens first, and probably something you open a lot. You don't want to have to swing the tire carrier open every time you need to just quickly grab something out the back of the truck. Swinging from the left and only having the swing half-length allows you to open the door without having to swing the carrier open.